“Every Mastodon account has an RSS feed that can be found by going to the user’s Mastodon page and adding ".rss" to the URL of that page.”
Mastodon has 12.8 million accounts, no CEO and no engagement algorithm, and every profile is already a feed. No API key, no login, no rate-limit tier. The project still has 61 open RSS issues. The most useful social feature on the network is a URL suffix.